Thermoplastic polymeric materials, including thermoplastic polymers and thermoplastic polymer alloys, can generally be processed using conventional plastics techniques, such as extrusion and injection molding. Because such processing techniques are advantageous for manufacturing, thermoplastic polymeric materials are used in a wide variety of applications including, for example, the manufacture of cord-reinforced polymeric articles such as hoses, conveyor belts, power train belts, transmission belts, and the like.
In every such cord-reinforced thermoplastic polymeric article, the cord or fiber should be firmly bonded to the thermoplastic polymeric material. This is so whether the fiber is a natural or synthetic polymer, or metallic, and whether the thermoplastic polymeric material is a thermoplastic polymer or a thermoplastic polymer alloy.
The manufacture of cord-reinforced rubber-based articles, such as tires, is well known. The conventional practice for manufacturing such cord-reinforced rubber-based articles has been to prepare the fiber by pretreatment with a combination of hexamethoxymelamine or hexamethylene-tetramine and a phenol-formaldehyde condensation product, wherein the phenol is almost always resorcinol. By a mechanism not completely understood, the resin reacts with the fiber and the rubber, effecting a firm reinforcing bond. Additionally, an increased need in the industry for fiber reinforcing of rubber to survive high dynamic stresses, such as flexing, for example, to avoid tire belt separation, has brought about a continuing search for other and better compositions and methods for achieving high adhesive strength between reinforcing fibers and rubber.
In view of the development of many thermoplastic polymeric materials which provide desirable physical properties similar to rubbers, i.e., softness, flexibility, and resilience, and the processing advantages of such thermoplastic polymeric materials, other and better compositions and methods for promoting adhesion between thermoplastic polymeric materials and substrates such as reinforcing fibers are similarly needed.